Swabbing often fails to detect amphibian chytridiomycosis under conditions of low infection load

Shin, Jaehyub, Bataille, Arnaud, Kosch, Tiffany A., and Waldman, Bruce (2014) Swabbing often fails to detect amphibian chytridiomycosis under conditions of low infection load. PLoS ONE, 9 (10). e111091. pp. 1-8.

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Abstract

The pathogenic chytrid fungus, Batrachochytrium dendrobatidis (denoted Bd), causes large-scale epizootics in naïve amphibian populations. Intervention strategies to rapidly respond to Bd incursions require sensitive and accurate diagnostic methods. Chytridiomycosis usually is assessed by quantitative polymerase chain reaction (qPCR) amplification of amphibian skin swabs. Results based on this method, however, sometimes yield inconsistent results on infection status and inaccurate scores of infection intensity. In Asia and other regions where amphibians typically bear low Bd loads, swab results are least reliable. We developed a Bd-sampling method that collects zoospores released by infected subjects into an aquatic medium. Bd DNA is extracted by filters and amplified by nested PCR. Using laboratory colonies and field populations of Bombina orientalis, we compare results with those obtained on the same subjects by qPCR of DNA extracted from swabs. Many subjects, despite being diagnosed as Bd-negative by conventional methods, released Bd zoospores into collection containers and thus must be considered infected. Infection loads determined from filtered water were at least 1000 times higher than those estimated from swabs. Subjects significantly varied in infection load, as they intermittently released zoospores, over a 5-day period. Thus, the method might be used to compare the infectivity of individuals and study the periodicity of zoospore release. Sampling methods based on water filtration can dramatically increase the capacity to accurately diagnose chytridiomycosis and contribute to a better understanding of the interactions between Bd and its hosts.

Item ID: 43976
Item Type: Article (Research - C1)
ISSN: 1932-6203
Additional Information:

© 2014 Shin et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Funders: National Research Foundation of Korea (NRF), Government of the Republic of Korea (MSIP), Seoul National University (SNU)
Projects and Grants: MSIP 2010-0002767, MSIP 2012R1A1A2044449, MSIP 012K1A2B1A03000496, SNU Brain Fusion Program, SNU Brain Korea 21 Program, SNU New Faculty Resettlement Fund grant
Date Deposited: 16 Mar 2016 07:36
FoR Codes: 06 BIOLOGICAL SCIENCES > 0605 Microbiology > 060505 Mycology @ 50%
06 BIOLOGICAL SCIENCES > 0602 Ecology > 060299 Ecology not elsewhere classified @ 50%
SEO Codes: 96 ENVIRONMENT > 9608 Flora, Fauna and Biodiversity > 960806 Forest and Woodlands Flora, Fauna and Biodiversity @ 50%
96 ENVIRONMENT > 9604 Control of Pests, Diseases and Exotic Species > 960404 Control of Animal Pests, Diseases and Exotic Species in Forest and Woodlands Environments @ 50%
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